Rex Heuermann’s family is “shocked,” “embarrassed’ and “disgusted” of the “animal” he’s accused of being, the top cop in the Long Island serial killer case said — as the FBI has helped raid relatives’ homes as far as South Carolina.

The accused Gilgo Beach killer lived in Massapequa Park with his two kids and second wife, Asa Ellerup, who police said had been away from home at the time of each of the four murders he’s so far suspected of committing.

“When we initially informed them about their husband, their father, they were shocked,” Suffolk County Police Commissioner Rodney Harrison told CNN Monday.

“They were disgusted — they were embarrassed.

“So, if you ask me, I don’t believe they knew about this double life that Mr. Heuermann was living,” he said.

Heuermann was arrested outside his Fifth Avenue office last Thursday through fears he might kill again or flee the country if he deduced he was about to be busted, Harrison said.

“It’s a very good thing that we got this animal off the streets,” the commissioner told CNN.

The Gilgo Beach task force is continuing to scour Heuermann’s Long Island home, which is just across South Oyster Bay from where the bodies of so-called “Gilgo Four” sex workers were found strewn in December 2010.

They have also searched a storage unit he had in Amityville while widening the search to consider if he continued killing after the Gilgo Beach murders, police have said.

The property searches have stretched at least 700 miles away to South Carolina where the FBI and local cops have raided properties tied to Heuermann and his relatives.

That includes around four lots of land Heuermann bought in Chester County exactly two years ago — telling locals he planned to retire to the secluded area, according to Fox Carolina.

His 57-year-old brother Craig — who once killed a police captain in a crash while drunk and “coked up” — lives on the same street as the Rippling Brooke Drive property, records show. He has not responded to The Post’s multiple attempts to reach him..

The Chester County Sheriff’s Office confirmed that it has helped “gather evidence” in the case — including getting a search warrant for the Chevrolet Avalanche that first linked Heuermann to the murders

His 57-year-old brother Craig — who once killed a police captain in a crash while drunk and “coked up” — lives on the same street as the Rippling Brooke Drive property, records show. He has not responded to The Post’s multiple attempts to reach him..

It was not clear how long the pickup — seen parked out Heuermann’s Long Island home after his alleged murders on Google Maps images — may have been at the wooded area in the Palmetto State.

The sheriff’s office said it “will continue to work closely” with the FBI and the Gilgo Beach task force “during this very important and arduous investigation.”

Heuermann has pleaded not guilty to murdering Melissa Barthelemy, Megan Waterman and Amber Costello.

A suspected serial killer has been arrested over the notorious Gilgo Beach murders in Long Island, The Post can confirm.

Rex Heuermann, 59, a married dad of two and architect at a New York City firm, has a home on 1st Avenue in Massapequa Park, sources told The Post.

His arrest is tied to the “Gilgo Four,” four women — Melissa Barthelemy, 24, Megan Waterman, 22, Amber Lynn Costello, 27, and Maureen Brainard-Barnes, 25 — found wrapped in burlap within days of each other in 2010.

The body of Barthelemy was first found along Ocean Parkway on Dec. 11, 2010, sparking fears of a serial killer in the area.